Display device

ABSTRACT

A display device comprising: a substrate having a display region; a plurality of temperature detection wires arranged at positions overlapping with the display region in plan view; and a light detection electrode overlapping with temperature detection regions of the temperature detection wires in plan view.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from Japanese Application No.2019-159318, filed on Sep. 2, 2019, the contents of which areincorporated by reference herein in its entirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a display device.

2. Description of the Related Art

What-are-called head-up displays (HUDs) that project an image onto amember having translucency, such as glass, have been known (for example,Japanese Patent Application Laid-open Publication No. 2015-210328(JP-A-2015-210328).

As described in the technique in JP-A-2015-210328, sunlight can beincident on a display device through an optical system. When the displaydevice is exposed to the sunlight condensed by the optical system, thedisplay device can be deteriorated.

Japanese Patent Application Laid-open Publication No. 2016-051090(JP-A-2016-051090) describes a liquid crystal display device in which atemperature sensor is arranged outside a display region. At a positionof the temperature sensor as in JP-A-2016-051090, temperature increasedue to sunlight condensed by an optical system and temperature increaseof a surrounding environment cannot be distinguished from each other.

SUMMARY

An object of the present disclosure is to provide a display devicecapable of detecting a partial heat generation state of a display regiondue to external light condensed by an optical system.

To solve the above-described problems and achieve the object, a displaydevice according to an aspect of the present disclosure includes asubstrate having a display region, a plurality of temperature detectionwires arranged at positions overlapping with the display region in planview, and a light detection electrode overlapping with a temperaturedetection region of the temperature detection wire in plan view.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a descriptive view for schematically explaining a head-updisplay;

FIG. 2 is a descriptive view for schematically explaining a displaydevice;

FIG. 3 is a descriptive view for explaining pixels of the displaydevice;

FIG. 4 is a plan view for explaining arrangement of temperaturedetection wires;

FIG. 5 is a cross-sectional view illustrating a schematic cross sectiontaken along line V-V′ of the display device illustrated in FIG. 4;

FIG. 6 is a cross-sectional view illustrating a schematic cross sectiontaken along line VI-VI′ of the display device illustrated in FIG. 4;

FIG. 7 is a schematic enlarged cross-sectional view for explaining thetemperature detection wires and light detection electrodes;

FIG. 8 is a plan view for explaining the light detection electrodes;

FIG. 9 illustrates a resistance change rate of one temperature detectionwire to a temperature thereof;

FIG. 10 is a descriptive view for explaining an example of distributionof the resistance change rates of the temperature detection wires;

FIG. 11 is a flowchart for explaining an example of determinationprocedures of a partial heat generation state of a display region;

FIG. 12 is a schematic enlarged cross-sectional view for explainingtemperature detection wires and light detection electrodes according toa second embodiment; and

FIG. 13 is a schematic enlarged cross-sectional view for explainingtemperature detection wires and light detection electrodes according toa third embodiment.

DETAILED DESCRIPTION

Modes (embodiments) for carrying out the present disclosure will bedescribed in detail with reference to the drawings. Contents describedin the following embodiments do not limit the present disclosure.Components described below include those that can be easily assumed bythose skilled in the art and substantially the same components.Furthermore, the components described below can be appropriatelycombined. The disclosure is merely an example and it is needless to saythat appropriate modifications within the gist of the disclosure atwhich those skilled in the art can easily arrive are encompassed in therange of the present disclosure. In the drawings, widths, thicknesses,shapes, and the like of the components can be schematically illustratedin comparison with actual modes for a clearer explanation. They are,however, merely examples and do not limit interpretation of the presentdisclosure. In the present specification and the drawings, the samereference numerals denote components similar to those described beforewith reference to the drawings that have been already referred to, anddetail explanation thereof can be appropriately omitted.

First Embodiment

FIG. 1 is a descriptive view for schematically explaining a head-updisplay. A head-up display (hereinafter, referred to as an HUD) device 1includes a backlight 6, a diffusion plate 9, a display device 2, awindow shield WS, and an optical system RM that enlarges an image fromthe display device 2 and projects it onto the window shield WS.

A housing 4 accommodates therein the backlight 6 functioning as a lightsource device, the display device 2 outputting an image using light Lfrom the backlight 6 as a light source, the diffusion plate 9 providedbetween the display device 2 and the backlight 6, and the optical systemRM. A part or all of the light L emitted from the backlight 6 passesthrough the display device 2 after being diffused by the diffusion plate9, is reflected by the optical system RM and the window shield WS, andreaches a user H to be recognized as an image VI in the field of view ofthe user H. That is to say, the display device 2 in the first embodimentfunctions as the head-up display (HUD) device 1 using the optical systemRM and the window shield WS. It is sufficient that the window shield WSis a member having translucency located on a line of sight of the userH, and the window shield WS may be, for example, a window screen of avehicle.

The HUD device 1 in the first embodiment guides the light L afterpassing through the display device 2 by the optical system RM includinga mirror member RM1 and a mirror member RM2. The mirror member RM1 is aplane mirror and the mirror member RM2 is a concave mirror. The mirrormember RM1 may be a concave mirror. The optical system RM is not limitedthereto, and the optical system RM may include one mirror member orthree or more mirror members.

Next, the display device 2 is described. FIG. 2 is a descriptive viewfor schematically explaining the display device. FIG. 3 is a descriptiveview for explaining pixels of the display device. FIG. 4 is a plan viewfor explaining arrangement of temperature detection wires. FIG. 5 is across-sectional view illustrating a schematic cross section taken alongline V-V′ of the display device illustrated in FIG. 4. FIG. 6 is across-sectional view illustrating a schematic cross section taken alongline VI-VI′ of the display device illustrated in FIG. 4. The displaydevice 2 in the first embodiment is a transmissive liquid crystaldisplay that outputs an image using the light L as the light source. Thedisplay device 2 includes a display driver integrated circuit (DDIC) 19.

The display device 2 is also referred to as a display panel. Asillustrated in FIG. 2, a large number of pixels VPix are arranged in amatrix with a row-column configuration in a display region AA of thedisplay device 2.

The pixels VPix illustrated in FIG. 3 have a plurality of subpixelsSPix. Each subpixel SPix includes a switching element Tr and a liquidcrystal capacitor 8 a. The switching element Tr is formed by a thin filmtransistor (TFT) and, in this example, is formed by an n-channel metaloxide semiconductor (MOS)-type TFT. An insulating layer 24 is providedbetween pixel electrodes PE and a common electrode CE, and they formholding capacitors 8 b illustrated in FIG. 3.

As illustrated in FIG. 2, a control circuit 110 functions as, forexample, a display control circuit 111 and a light source controlcircuit 112. The display control circuit 111 outputs, to the DDIC 19, amaster clock, a horizontal synchronization signal, a verticalsynchronization signal, pixel signals, a drive instruction signal of thebacklight 6, and the like. The pixel signals are, for example, signalsprovided by combining individual gradation values of red (R), green (G),and blue (B). The display control circuit 111 has a function ofcontrolling output gradation values of some or all of the pixels basedon light emission amounts of light sources 61 that are controlled by thelight source control circuit 112. The light source control circuit 112controls operations of the light sources 61 in synchronization with thepixel signals.

The switching elements Tr of the respective subpixels SPix, signal linesSGL, scan lines GCL, and the like illustrated in FIG. 3 are formed on afirst substrate 10 (see FIG. 5). The signal lines SGL are wires forsupplying the pixel signals to the pixel electrodes PE illustrated inFIG. 5. The scan lines GCL are wires for supplying drive signals fordriving the switching elements Tr. The signal lines SGL and the scanlines GCL extend in a plane parallel to the surface of the firstsubstrate 10 illustrated in FIG. 5.

As illustrated in FIG. 3, light shielding layers BM are formed along thesignal lines SGL and the scan lines GCL. Although in FIG. 3, electricconnection of the switching elements Tr is illustrated, the lightshielding layers BM are superimposed on the switching elements Tractually. The subpixels SPix have openings surrounded by the lightshielding layers BM, and a set of color filters CFR, CFG, and CFB thatare respectively colored with three colors of red (R), green (G), andblue (B) is made to correspond to the openings of the subpixels SPixillustrated in FIG. 3. A set of the subpixels SPix corresponding thecolor filters CFR, CFG, and CFB of three colors configures the pixelVPix. The color filters may include color regions of four or morecolors.

The DDIC 19 illustrated in FIG. 2 selects, as a gate driver, the scanline GCL in order. The DDIC 19 applies a scan signal to the gates of theswitching elements Tr of the subpixels Pix via the selected scan lineGCL. One row (one horizontal line) of the subpixels SPix is therebyselected as a display drive target in order.

The DDIC 19 supplies, as a source driver, pixel signals to the subpixelsPix forming the selected one horizontal line via the signal lines SGL.Display is performed on these subpixels SPix on a horizontal line basisin accordance with the supplied pixel signals.

The DDIC 19 applies, as a common electrode driver, a common potential tothe common electrode CE. The common potential is a direct-current (DC)voltage signal that is commonly applied to the subpixels SPix.

As described above, the DDIC 19 functions as the gate driver, the sourcedriver, and the common electrode driver. The DDIC 19 may be configuredsuch that the gate driver, the source driver, and the common electrodedriver are separated from one another. At least one of the gate driver,the source driver, and the common electrode driver may be formed on thefirst substrate 10 using a thin film transistor (TFT).

As illustrated in FIG. 2, a plurality of temperature detection wires SMare arrayed. Both terminals of the temperature detection wires SM areextended and are electrically coupled to a resistance detection circuit120. The resistance detection circuit 120 performs AD conversion onresistances of the temperature detection wires SM and outputs resistancedetection signals to the control circuit 110.

As illustrated in FIG. 2, a plurality of light detection electrodes LSare arrayed. Both terminals of the light detection electrodes LS areextended and are electrically coupled to the resistance detectioncircuit 120. The resistance detection circuit 120 performs AD conversionon resistances of the light detection electrodes LS and outputsresistance detection signals to the control circuit 110.

In the first embodiment, a detection region in which one temperaturedetection wire SM is arranged and a detection region in which one lightdetection electrode LS is arranged overlap with each other in plan view.

Next, details of the configuration example of the display device 2 inthe first embodiment are described. As illustrated in FIG. 5, thedisplay device 2 includes an array substrate SUB1, a counter substrateSUB2, and a liquid crystal layer LC as a display function layer. Thecounter substrate SUB2 is arranged so as to face the surface of thearray substrate SUB1 in the vertical direction. The liquid crystal layerLC is provided between the array substrate SUB1 and the countersubstrate SUB2.

In the first embodiment, the direction toward a second substrate 20 ofthe counter substrate SUB2 from the first substrate 10 in the directionperpendicular to the surface of the first substrate 10 of the countersubstrate SUB2 is an “upward direction”. The direction toward the firstsubstrate 10 from the second substrate 20 is a “downward direction”.

The array substrate SUB1 includes the first substrate 10, the pixelelectrodes PE, the common electrode CE, and a polarizing plate PL1. Theswitching elements Tr such as thin film transistors (TFTs) and varioustypes of wiring (not illustrated in FIG. 5) such as the scan lines GCLand the signal lines SGL are provided on the first substrate 10.

The common electrode CE is provided above the first substrate 10. Thepixel electrodes PE are provided above the common electrode CE with theinsulating layer 24 interposed therebetween. The pixel electrodes PE areprovided in a different layer from the common electrode CE and arearranged so as to be superimposed on the common electrode CE in planview. The pixel electrodes PE are arranged in a matrix with a row-columnconfiguration in plan view. The polarizing plate PL1 is provided underthe first substrate 10 with an adhesive layer 66 interposedtherebetween. The pixel electrodes PE and the common electrode CE aremade of, for example, a conductive material having translucency, such asindium tin oxide (ITO). Although the first embodiment describes theexample in which the pixel electrodes PE are provided above the commonelectrode CE, the common electrode CE may be provided above the pixelelectrodes PE.

The DDIC 19 and a flexible substrate 71 are provided on the firstsubstrate 10. The DDIC 19 functions as the control circuit 110illustrated in FIG. 1.

The counter substrate SUB2 includes the second substrate 20, the lightshielding layers BM formed on one surface of the second substrate 20,the light detection electrodes LS provided on the other surface of thesecond substrate 20, the temperature detection wires SM, a protectionlayer 38, an adhesive layer 39, and a polarizing plate PL2. Asillustrated in FIG. 6, the color filters CFR, CFG, and CFB are alsoformed on one surface of the second substrate 20 similarly to the lightshielding layers BM.

As illustrated in FIG. 4, the temperature detection wires SM are arrayedon the second substrate 20. As illustrated in FIG. 5, a flexiblesubstrate 72 is coupled to the second substrate 20. The temperaturedetection wires SM are electrically coupled to the flexible substrate 72with terminal portions 36 interposed therebetween. The flexiblesubstrate 71 is coupled to the resistance detection circuit 120illustrated in FIG. 2. The detail configuration of the temperaturedetection wires SM will be described later.

The protection layer 38 is an insulating layer for protecting thetemperature detection wires SM. The protection layer 38 can be made oftranslucent resin such as acrylic resin. The light detection electrodesLS are formed on the protection layer 38. In other words, thetemperature detection wires SM and the light detection electrodes LS areprovided above a second substrate 31, and the temperature detectionwires SM are stacked below the light detection electrodes LS. Theprotection layer 38 electrically insulates the light detectionelectrodes LS and the temperature detection wires SM from each other.

The light detection electrodes LS are made of a material havingtranslucency and conductivity. The light detection electrodes LS aremade of, for example, ITO, indium zinc oxide (IZO), SnO, or an organicconductive film. The light detection electrodes LS may be formed by anoxide film containing tin oxide (SnO₂) and silicon dioxide (Sift) asmain components, an oxide layer containing gallium oxide (Ga₂O₃), indiumoxide (In₂O₃), and tin oxide (SnO₂) as main components, or a translucentconductive layer made of ITO as a main material and containing silicon(Si). As illustrated in FIG. 5, the polarizing plate PL2 is provided onthe light detection electrodes LS with the adhesive layer 39 interposedtherebetween.

A first optical device OD1 including the polarizing plate PL1 isarranged on the outer surface of the first substrate 10 or on thesurface thereof facing the backlight 6 (see FIG. 2). A second opticaldevice OD2 including the polarizing plate PL2 is arranged on the outersurface of the second substrate 20 or on the surface thereof on anobservation position side. A first polarization axis of the polarizingplate PL1 and a second polarization axis of the polarizing plate PL2have a crossed Nicol positional relation in plan view. The first opticaldevice OD1 and the second optical device OD2 may include another opticallayer such as a retardation plate.

The first substrate 10 and the second substrate 20 are arranged with apredetermined interval. A space between the first substrate 10 and thesecond substrate 20 is sealed by a seal portion 69. The liquid crystallayer LC is provided in a space surrounded by the first substrate 10,the second substrate 20, and the seal portion 69. The liquid crystallayer LC modulates light that passes therethrough in accordance with anelectric field state, and liquid crystal in a transverse electric fieldmode such as in-plane switching (IPS) including fringe field switching(FFS) is used therefor. Orientation layers (not illustrated) arerespectively arranged between the liquid crystal layer LC and the arraysubstrate SUB1 and between the liquid crystal layer LC and the countersubstrate SUB2 illustrated in FIG. 5. In the first embodiment, theliquid crystal layer LC is driven with a transverse electric field thatis generated between the pixel electrodes PE and the common electrodeCE.

The backlight 6 illustrated in FIG. 1 and FIG. 2 is provided under thefirst substrate 10. The light from the backlight 6 passes through thearray substrate SUB1 and is modulated in accordance with the liquidcrystal state at the corresponding position. A transmission state of thelight to a display surface changes depending on places. An image isthereby displayed in the display region AA of the display device 2.

Next, the cross section along line VI-VI′ illustrated in FIG. 4 will bedescribed in detail. In FIG. 6, the array substrate SUB1 includes, as abase body, the first substrate 10 having translucency and an insulatingproperty, such as a glass substrate and a resin substrate. The arraysubstrate SUB1 includes a first insulating layer 11, a second insulatinglayer 12, a third insulating layer 13, the signal lines SGL, the pixelelectrodes PE, the common electrode CE, and a first orientation film AL1on the side of the first substrate 10 that faces the counter substrateSUB2.

Although not observed in the cross section of FIG. 6, the scan lines GCLand gate electrodes of the switching elements Tr (see FIG. 4) areprovided on the first substrate 10, and the first insulating layer 11illustrated in FIG. 6 covers the scan lines GCL and the gate electrodesGE (see FIG. 4). An insulating layer made of an inorganic materialhaving translucency, such as silicon oxide and silicon nitride, may beformed under the first insulating layer 11, the scan lines GCL, and thegate electrodes.

Although not observed in the cross section of FIG. 6, a semiconductorlayer of the switching elements Tr (see FIG. 4) is stacked on the firstinsulating layer 11. The semiconductor layer is made of, for example,amorphous silicon but may be made of polysilicon or an oxidesemiconductor.

As illustrated in FIG. 6, the second insulating layer 12 covers thesignal lines SGL. The second insulating layer 12 is made of a resinmaterial having translucency, such as acrylic resin, and has a filmthickness that is larger than those of the other insulating films madeof the inorganic material. It should be noted that the second insulatinglayer 12 may be made of an inorganic material.

Although not observed in the cross section of FIG. 6, source electrodesof the switching elements Tr (see FIG. 4) covering parts of thesemiconductor layer and drain electrodes of the switching elements Tr(see FIG. 4) covering parts of the semiconductor layer are provided onthe second insulating layer 12. The drain electrodes are made of thesame material as that of the signal lines SGL. The third insulatinglayer 13 is provided on the semiconductor layer of the switchingelements Tr (see FIG. 4). The switching elements Tr as described aboveare of a bottom gate type but may be of a top gate type.

The common electrode CE is located on the second insulating layer 12. InFIG. 6, the common electrode CE faces the signal lines SGL with thethird insulating layer 13 interposed therebetween. The third insulatinglayer 13 is made of an inorganic material having translucency, such assilicon oxide and silicon nitride.

The common electrode CE is covered by the third insulating layer 13. Thethird insulating layer 13 is formed by, for example, an inorganicmaterial having translucency, such as silicon oxide and silicon nitride.

The pixel electrodes PE are located on the third insulating layer 13 andface the common electrode CE with the third insulating layer 13interposed therebetween. The pixel electrodes PE and the commonelectrode CE are made of, for example, a conductive material havingtranslucency, such as indium tin oxide (ITO) and indium zinc oxide(IZO). The pixel electrodes PE are covered by the first orientation filmALL The first orientation film AL1 also covers the third insulatinglayer 13.

The counter substrate SUB2 includes, as a base body, the secondsubstrate 20 having translucency and an insulating property, such as aglass substrate and a resin substrate. The counter substrate SUB2includes the light shielding layers BM, the color filters CFR, CFG, andCFB, an overcoat layer OC, and a second orientation film AL2 on the sideof the second substrate 20 that faces the array substrate SUB1.

As illustrated in FIG. 6, the light shielding layers BM are located onthe side of the second substrate 20 that faces the array substrate SUB1.As illustrated in FIG. 6, the light shielding layers BM define openingsAP that respectively face the pixel electrodes PE. The light shieldinglayers BM are made of a resin material of black color or a metalmaterial having a light shielding property.

The color filters CFR, CFG, and CFB are located on the side of thesecond substrate 20 that faces the array substrate SUB1, and endportions thereof overlap with the light shielding layers BM. As anexample, the color filters CFR, CFG, and CFB are made of a resinmaterial colored with blue, red, and green, respectively.

The overcoat layer OC covers the color filters CFR, CFG, and CFB. Theovercoat layer OC is made of a resin material having translucency. Thesecond orientation film AL2 covers the overcoat layer OC. The firstorientation film AL1 and the second orientation film AL2 are made of,for example, a material exhibiting horizontal orientation performance.

The counter substrate SUB2 includes the light shielding layers BM andthe color filters CFR, CFG, and CFB. The light shielding layers BM arearranged in a region facing wire portions including the scan lines GCL,the signal lines SGL, and the switching elements Tr illustrated in FIG.3.

In FIG. 6, the counter substrate SUB2 includes the color filters CFR,CFG, and CFB of three colors. Alternatively, the counter substrate SUB2may include color filters of four or more colors that include colorfilters of different colors from blue, red, and green, for example,white, clear, yellow, magenta, and cyan. The array substrate SUB1 mayinclude these color filters CFR, CFG, and CFB.

The array substrate SUB1 and the counter substrate SUB2 described aboveare arranged such that the first orientation film AL1 and the secondorientation film AL2 face each other. The liquid crystal layer LC issealed into between the first orientation film AL1 and the secondorientation film AL2. The liquid crystal layer LC is made of a negativeliquid crystal material having a negative dielectric anisotropy or apositive liquid crystal material having a positive dielectricanisotropy.

The array substrate SUB1 faces the backlight 6 (see FIG. 1), and thecounter substrate SUB2 is located on the display surface side. Variousmodes can be applied to the backlight 6, and explanation of the detailconfiguration thereof is omitted.

For example, when the liquid crystal layer LC is made of the negativeliquid crystal material and in a state in which no voltage is applied tothe liquid crystal layer LC, liquid crystal molecules LM are initiallyoriented in such a direction that long axes thereof are along a firstdirection Dx in a Dx-Dy plane illustrated in FIG. 4. On the other hand,in a state in which the voltage is applied to the liquid crystal layerLC, that is, in an ON state in which an electric field is formed betweenthe pixel electrodes PE and the common electrode CE, the liquid crystalmolecules LM receive influences of the electric field and orientationstates thereof are changed. In the ON state, a polarization state ofincident linearly polarized light is changed in accordance with theorientation states of the liquid crystal molecules LM when passingthrough the liquid crystal layer LC.

Then, the temperature detection wires SM will be described in detail. Asillustrated in FIG. 4, each of the temperature detection wires SMincludes a plurality of conductive thin wires 33, a first coupling wire34 a, and a second coupling wire 34 b. One ends of the conductive thinwires 33 are electrically coupled to each other by the first couplingwire 34 a, and the other ends of the conductive thin wires 33 areelectrically coupled to each other by the first coupling wire 34 a.

The conductive thin wires 33 are formed by a metal layer made of one ormore elements selected from aluminum (Al), copper (Cu), silver (Ag),molybdenum (Mo), chrome (Cr), titanium (Ti), and tungsten (W).Alternatively, the conductive thin wires 33 are formed by a metal layermade of an alloy containing one or more elements selected from aluminum(Al), copper (Cu), silver (Ag), molybdenum (Mo), chrome (Cr), titanium(Ti), and tungsten (W). The conductive thin wires 33 can be made of, forexample, an aluminum alloy such as AlNd, AlCu, AlSi, and AlSiCu. Theconductive thin wires 33 may be a multilayer body formed by stacking aplurality of conductive layers made of the above-mentioned metalmaterial or the alloy containing one or more of the above-mentionedmaterials.

A width Wsm of the conductive thin wires 33 (temperature detection wiresSM) illustrated in FIG. 6 is a length orthogonal to the lengthwisedirection and is, for example, preferably 1 μm to 10 μm, and morepreferably in a range of 1 μm to 5 μm. When the width Wsm is 10 μm orsmaller, the width Wsm can be made less than a width Wbm of the lightshielding layers. This is preferable because the possibility that anaperture ratio is decreased is lowered. When the width Wsm is 1 μm orgreater, the shapes of the conductive thin wires 33 (temperaturedetection wires SM) are made stable. This is also preferable because thepossibility that the conductive thin wires 33 are decoupled is lowered.

First wires 37 a are respectively coupled to the first coupling wires 34a. Second wires 37 b are respectively coupled to the second couplingwires 34 b. That is to say, in the first embodiment, the first wires 37a are coupled on the side of one ends of the temperature detection wiresSM, and the second wires 37 b are coupled on the side of the other endsthereof. The first wires 37 a are provided along a peripheral region FR.The second wires 37 b are provided along the peripheral region FR.

The first wire 37 a and the second wire 37 b coupled to one temperaturedetection wire SM are coupled to the different terminal portions 36.That is to say, the first wires 37 a as one ends of the temperaturedetection wires SM and the second wires 37 b as the other ends of thetemperature detection wires SM are extended to the flexible substrate 72with the terminal portions 36 interposed therebetween. The first wires37 a of the temperature detection wires SM and the second wires 37 b ofthe temperature detection wires SM are electrically coupled to theresistance detection circuit 120 illustrated in FIG. 2 with the flexiblesubstrate 72 interposed therebetween. In the resistance detectioncircuit 120, resistance change in accordance with temperature change isdetected between the first wires 37 a as one ends of the temperaturedetection wires SM and the second wires 37 b as the other ends of thetemperature detection wires SM.

The first wires 37 a and the second wires 37 b can be made of the samematerial as the metal material, the alloy, or the like that is used forthe conductive thin wires 33. It is sufficient that the first wires 37 aand the second wires 37 b are made of a material having preferableconductivity, and a material differing from that of the conductive thinwires 33 may be used.

One ends of the conductive thin wires 33 are electrically coupled toeach other by being coupled by the first coupling wires 34 a. The otherends of the conductive thin wires 33 are electrically coupled to eachother by being coupled by the second coupling wires 34 b. The firstwires 37 a are electrically coupled to the first coupling wires 34 a,and the second wires 37 b are electrically coupled to the secondcoupling wires 34 b. The display region AA in which the conductive thinwires 33 coupled by the first coupling wires 34 a and the secondcoupling wires 34 b are arranged corresponds to temperature detectionregions of the temperature detection wires SM. With this configuration,the temperature detection wires SM can detect a partial heat generationstate of the display region AA in a range of a predetermined area.Resistance values of the temperature detection wires SM are adjusted inaccordance with the number of conductive thin wires 33.

The conductive thin wires 33 are arranged at positions overlapping withthe light shielding layers BM in plan view. As illustrated in FIG. 5,the conductive thin wires 33 extend in the first direction along thelight shielding layers BM. The planar shape of the conductive thin wires33 is not limited to a linear metal thin wire shape. When the signallines SGL have a zigzag shape or a wavy line shape, for example, theplanar shape of the conductive thin wires 33 may be a zigzag shape or awavy line shape along the shape of the signal lines SGL.

As illustrated in FIG. 4, the width of slits SP between the adjacenttemperature detection wires SM in a second direction Dy is desirably thesame as an interval between the adjacent conductive thin wires 33. Theintervals of the conductive thin wires 33 are thereby made uniform inthe plane, so that undesired diffraction light is reduced.

In FIG. 6, eight light shielding layers BM that do not overlap with theconductive thin wires 33 are formed between one light shielding layer BMthat overlaps with the conductive thin wire 33 and another lightshielding layer BM that overlaps with the conductive thin wire 33. Dummyconductive thin wires that are not electrically coupled to the firstwires 37 a and the second wires 37 b may be provided, and the dummyconductive thin wires may be superimposed on the light shielding layersBM that do not overlap with the conductive thin wires 33.

FIG. 8 is plan view for explaining the light detection electrodes. Asillustrated in FIG. 8, the light detection electrodes LS are formed onsubstantially the entire surface of the second substrate 20 and areprovided over the entire surface of the display region AA and theperipheral region FR. As illustrated in FIG. 8, the light detectionelectrodes LS are divided by slits SPP.

In the first embodiment, one light detection electrode LS overlaps withone temperature detection wire SM. The area of the light detectionelectrodes LS in plan view is larger than the total area of thetemperature detection wires SM. The slits SP (see FIG. 4) between theadjacent temperature detection wires SM and the slits SPP (see FIG. 8)between the adjacent light detection electrodes LS overlap with eachother in plan view.

In the first embodiment, third wires 37 c are coupled on the side of oneends of the light detection electrodes LS and fourth wires 37 d arecoupled on the side of the other end thereof. The third wires 37 c areprovided along the peripheral region FR. The fourth wires 37 d areprovided along the peripheral region FR. The third wires 37 c are notelectrically coupled to the temperature detection wires SM. The fourthwires 37 d are not electrically coupled to the temperature detectionwires SM.

The third wire 37 c and the fourth wire 37 d coupled to one lightdetection electrode LS are coupled to the different terminal portions36. That is to say, the third wires 37 c as one ends of the lightdetection electrodes LS and the fourth wires 37 d as the other ends ofthe light detection electrodes LS are extended to the flexible substrate72 with the terminal portions 36 interposed therebetween. The thirdwires 37 c of the light detection electrodes LS and the fourth wires 37d of the light detection electrodes LS are electrically coupled to theresistance detection circuit 120 illustrated in FIG. 2 with the flexiblesubstrate 72 interposed therebetween. In the resistance detectioncircuit 120, resistance change in accordance with a light amount isdetected between the third wires 37 c as one ends of the light detectionelectrodes LS and the fourth wires 37 d as the other ends of the lightdetection electrodes LS.

The third wires 37 c and the fourth wires 37 d can be made of the samematerial as the conductive material that is used for the light detectionelectrodes LS or the material that is used for the conductive thin wires33. It is sufficient that the light detection electrodes LS are made ofa material having preferable conductivity, and a material differing fromthose of the light detection electrodes LS and the conductive thin wires33 may be used therefor.

As described above, the display device 2 in the first embodimentincludes the substrate having the display region AA, the temperaturedetection wires SM, and the light detection electrodes LS. Thetemperature detection wires SM are arranged at positions overlappingwith the display region AA in plan view. The light detection electrodesLS overlap with the temperature detection regions of the temperaturedetection wires. With this configuration, light of sunlight LL and thepartial heat generation state of the display region AA can be detectedin the temperature detection regions of the temperature detection wiresSM.

In the first embodiment, conductive layers 331 are formed on the secondsubstrate 20. Conductive layers 332 are formed on the conductive layers331. The protection layer 38 is formed on the conductive layers 331 andthe conductive layers 332. The protection layer 38 is made oftranslucent resin having an insulating property, such as acrylic resin.The light detection electrodes LS are formed on the protection layer 38.In other words, the temperature detection wires SM and the lightdetection electrodes LS are provided above the second substrate 20 andthe temperature detection wires SM are stacked below the light detectionelectrodes LS.

The resistances of the light detection electrodes LS are lowered whenthey are irradiated with the sunlight LL. On the other hand, thetemperatures of the temperature detection wires SM are increased and theresistances thereof are increased when they are irradiated with thesunlight LL.

The light detection electrodes LS overlap with the temperature detectionregions of the temperature detection wires SM in plan view. Theresistance detection circuit 120 cannot therefore detect the resistancechange accurately when the light detection electrodes LS and thetemperature detection wires SM are electrically coupled to each other.To cope with this, in the first embodiment, the light detectionelectrode LS and the temperature detection wires SM are insulated fromeach other with the protection layer 38. With this configuration, theresistance detection circuit 120 can detect the resistance change ratesin accordance with change in the light amount of the light detectionelectrodes LS.

Furthermore, the resistance detection circuit 120 can detect theresistance change rates in accordance with change in the temperatures ofthe temperature detection regions of the temperature detection wires SM.

The light detection electrodes LS are made of, for example, one or morematerials selected from ITO, indium zinc oxide (IZO), and SnO.

The conductive layers 331 may be multilayer bodies in which at least twoor more metal layers made of one or more elements selected from aluminum(Al), copper (Cu), silver (Ag), molybdenum (Mo), chrome (Cr), titanium(Ti), and tungsten (W), and a metal layer made of an alloy containingany of these elements are stacked. Similarly, the conductive layers 332may be multilayer bodies in which at least two or more metal layers madeof one or more elements selected from aluminum (Al), copper (Cu), silver(Ag), molybdenum (Mo), chrome (Cr), titanium (Ti), and tungsten (W), ametal layer made of an alloy containing any of these elements, an oxidefilm containing tin oxide (SnO₂) and silicon dioxide (SiO₂) as maincomponents, and an oxide layer containing gallium oxide (Ga₂O₃), indiumoxide (In₂O₃), and tin oxide (SnO₂) as main components are stacked.

A material causing light reflection that is less than that by conductivelayers 331 is selected for the conductive layers 332. Accordingly, thevisible light reflectivity of the conductive layers 332 is lower thanthe visible light reflectivity of the conductive layer 331, and theconductive layers 332 are closer in color to black than the conductivelayers 331. A resistance value of the conductive layers 332 is increasedin order to make them closer to black than the conductive layers 331.Accordingly, a material having higher conductivity than that of theconductive layers 332 is selected for the conductive layers 331.Increase in power consumption in the temperature detection wires SM canthereby be reduced.

Measurement of Temperature

FIG. 9 illustrates the resistance change rate of one temperaturedetection wire to the temperature thereof. FIG. 10 is a descriptive viewfor explaining an example of distribution of the resistance change ratesof the temperature detection wires. FIG. 11 is a flowchart forexplaining an example of determination procedures of the partial heatgeneration state of the display region. As illustrated in FIG. 9, theresistance change rate of the temperature detection wire SM withreference to a resistance value of a reference temperature, for example,linearly changes depending on temperatures.

As illustrated in FIG. 1, in the HUD device 1, the sunlight LL can beincident on an opening 4S of the housing 4 depending on a relativeposition of sun SUN. The sunlight LL is guided by the optical system RM,is condensed as is closer to the display device 2, and strikes on a partof the display region in some cases. The condensed sunlight possiblydeteriorates the display device, and it is therefore desired that apartial heat generation state of the display region is detected.

In the first embodiment, as illustrated in FIG. 4, the temperaturedetection wires SM are arrayed at the positions overlapping with thedisplay region AA in plan view. When there is the temperature detectionwire SM the temperature of which is increased, the position of thedisplay region AA exposed to the sunlight LL can be grasped.

For example, in FIG. 4, it is assumed that the temperature detectionwires SM of the temperature detection wire SM1 to the temperaturedetection wire SMk illustrated in FIG. 10 are arrayed in the Dydirection in the display region AA. The resistance detection circuit 120illustrated in FIG. 2 performs AD conversion on the resistances of thetemperature detection wire SM1 to the temperature detection wire SMk andoutputs resistance detection signals to the control circuit 110.

As illustrated in FIG. 11, the control circuit 110 detects theresistance change rates of the temperature detection wires SM1 to SMk.When there is no temperature detection wire the resistance change rateof which is equal to or higher than a predetermined threshold Thr (No atstep ST1), the control circuit 110 continues detection of the resistancechange rates of the temperature detection wires SM1 to SMk.

When there is the temperature detection wire SM9 the resistance changerate of which is equal to or higher than the predetermined threshold Thr(Yes at step ST1), the control circuit 110 detects the resistance changerate of the light detection electrode overlapping with the temperaturedetection wire SM9 specified at step ST1 in plan view. When theresistance change rate of the light detection electrode overlapping withthe temperature detection wire SM9 specified at step ST1 in plan view isnot higher than the threshold (No at step ST2), the control circuit 110continues detection of the resistance change rates of the temperaturedetection wires SM1 to SMk.

When the resistance change rate of the light detection electrodeoverlapping with the temperature detection wire SM9 specified at stepST1 in plan view is higher than the threshold (Yes at step ST2), thecontrol circuit 110 determines that the temperature detection wire SM9specified at step ST1 is exposed to the sunlight LL (step ST3).

The control circuit 110 can detect temperature increase due to thesunlight LL condensed by the optical system RM while distinguishing itfrom temperature increase of a surrounding environment.

When the temperature detection wires SM are exposed to the sunlight LL,the sunlight LL can be reflected by the temperature detection wires SM.As illustrated in FIG. 1, even when a mounting position of the displaydevice 2 is adjusted so as to prevent regularly reflected light of thesunlight LL from returning to the window shield WS, there is thepossibility that diffraction light generated in the conductive thinwires 33 reaches the window shield WS.

As illustrated in FIG. 7, in the display device 2, the temperaturedetection wires SM are arranged at positions overlapping with the secondsubstrate 20 having the display region in the display region AA in planview. The temperature detection wires SM include the first conductivelayers 331 stacked above the second substrate 20 and the secondconductive layers 332 stacked on the first conductive layers 331. Thevisible light reflectivity of the second conductive layers 332 is lowerthan the visible light reflectivity of the first conductive layer 331.With this configuration, even when the temperature detection wires SMare exposed to the sunlight LL, the diffraction light on the temperaturedetection wires SM is reduced. As a result, display quality of the imageVI that is recognized in the field of view of the user H illustrated inFIG. 1 is improved.

As illustrated in FIG. 7, the second conductive layers 332 have a largerwidth than the first conductive layers 331 does. With these widths, evenwhen the first conductive layers 331 reflect the sunlight LL, the secondconductive layers 332 cover the light, so that the diffraction light onthe temperature detection wires SM is reduced.

Second Embodiment

FIG. 12 a schematic enlarged cross-sectional view for explainingtemperature detection wires and light detection electrodes according toa second embodiment. The same reference numerals denote the samecomponents described in the above-mentioned first embodiment andoverlapped explanation thereof is omitted.

In the second embodiment, an insulating layer 52 is formed on the lightdetection electrode LS. The conductive layers 331 are formed on theinsulating layer 52. The conductive layers 332 are formed on theconductive layers 331. With this configuration, the light detectionelectrode LS and the above-mentioned conductive thin wires 33 areinsulated from each other with the insulating layer 52. In other words,the temperature detection wires SM are stacked above the light detectionelectrode LS with the insulating layer 52 interposed therebetween.

In the second embodiment, the light detection electrode LS and thetemperature detection wires SM are insulated from each other with theinsulating layer 52. With this configuration, the resistance detectioncircuit 120 can detect the resistance change rates in accordance withchange in the light amount of the light detection electrode LS.Furthermore, the resistance detection circuit 120 can detect theresistance change rates in accordance with change in the temperatures ofthe temperature detection regions of the temperature detection wires SM.

Third Embodiment

FIG. 13 a schematic enlarged cross-sectional view for explainingtemperature detection wires and light detection electrodes according toa third embodiment. The same reference numerals denote the samecomponents described in the above-mentioned first embodiment and secondembodiment and overlapped explanation thereof is omitted.

In the third embodiment, the light detection electrodes LS are formed inthe same layer as the conductive thin wires 33. The light detectionelectrodes LS are formed between the adjacent conductive thin wires 33and they are insulated from each other with the protection layer 38. Inother words, the light detection electrodes LS and the temperaturedetection wires SM are formed in the same layer on the second substrate20.

In the third embodiment, the light detection electrodes LS and thetemperature detection wires SM are insulated from each other with theprotection layer 38. With this configuration, the resistance detectioncircuit 120 can detect the resistance change rates in accordance withchange in the light amount of the light detection electrodes LS.Furthermore, the resistance detection circuit 120 can detect theresistance change rates in accordance with change in the temperatures ofthe temperature detection regions of the temperature detection wires SM.

Other effects provided by the aspect described in the first embodimentthat are obvious from the present disclosure or at which those skilledin the art can appropriately arrive should be interpreted to be providedby the present invention.

Although the preferred embodiments have been described above, thepresent disclosure is not limited by these embodiments. Contentsdisclosed in the embodiments are merely examples and variousmodifications can be made in a range without departing from the gist ofthe present disclosure. It is needless to say that appropriatemodifications in a range without departing from the gist of the presentdisclosure belong to the technical range of the present disclosure.

For example, although the light detection electrodes LS are divided bythe slits SPP, the light detection electrode LS may be a solid filmcovering the display region AA by one material having translucency andconductivity without forming the slits SPP.

For example, although the display device 2 is the liquid crystal panel,the display device 2 may be an organic EL panel. The display device 2may be a micro LED that displays an image by outputting different lightfrom each light emitting element LED. The light emitting element LED hasa size of approximately 3 μm to 100 μm in plan view.

What is claimed is:
 1. A display device comprising: a substrate having adisplay region; a plurality of temperature detection wires arranged atpositions overlapping with the display region in plan view; and a lightdetection electrode overlapping with temperature detection regions ofthe temperature detection wires in plan view.
 2. The display deviceaccording to claim 1, wherein one end of each of the temperaturedetection wires is coupled to a first wire, the other end of each of thetemperature detection wires is coupled to a second wire, and resistancethat changes in accordance with temperature change is detected betweenthe first wire and the second wire, and one end of the light detectionelectrode is coupled to a third wire, the other end of the lightdetection electrode is coupled to a fourth wire, and resistance thatchanges in accordance with a light amount is detected between the thirdwire and the fourth wire.
 3. The display device according to claim 1,wherein the light detection electrode is made of a material havingtranslucency and conductivity.
 4. The display device according to claim2, wherein the light detection electrode is made of a material havingtranslucency and conductivity.
 5. The display device according to claim1, wherein the temperature detection wires are stacked above or belowthe light detection electrode.
 6. The display device according to claim2, wherein the temperature detection wires are stacked above or belowthe light detection electrode.
 7. The display device according to claim3, wherein the temperature detection wires are stacked above or belowthe light detection electrode.
 8. The display device according to claim1, wherein the temperature detection wires are formed in a same layer asthe light detection electrode.
 9. The display device according to claim2, wherein the temperature detection wires are formed in a same layer asthe light detection electrode.
 10. The display device according to claim3, wherein the temperature detection wires are formed in a same layer asthe light detection electrode.